Why render time in blender is increasing 10 times after rotating 3d model?
I've posted at Blender's bug tracker and it seemed for first look as a bug, but 
Brecht Van Lommel (Rendering Software Engineer) explained:


  This is a typical issue with raytracers, many long thin faces along one direction are difficult to fit well in a BVH unless the faces are aligned to the X/Y/Z axis.
  Also, the workaround is to subdivide the object more so the faces are not so long.




After subdivision mesh along faces render time decreased much.

LINK to this discussion on Blender's tracker.